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From: "Valdis Klētnieks" <valdis.kletnieks@vt.edu>
To: John Wood <john.wood@gmx.com>
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: Notify special task kill using wait* functions
Date: Sat, 03 Apr 2021 17:34:01 -0400	[thread overview]
Message-ID: <145687.1617485641@turing-police> (raw)
In-Reply-To: <20210403070226.GA3002@ubuntu>


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On Sat, 03 Apr 2021 09:02:26 +0200, John Wood said:

> Currently, the scenario you propose is fully mitigated :). And notifying to
> userspace that all the tasks has been killed by "Brute" not decrease the
> security. It adds the possibility that the supervisor adopts the correct policy.

So how do you figure out how far up the chain you kill processes?

What does a triple or quadruple fork do? How do you ensure that you deliver
the notification to the correct supervisor? (Hint - walking backwards until you
hit a process running as root isn't necessarily the right answer, especially
once you consider containers and systems where gdm runs as non-root
and other weird stuff..)

Bonus points if you deal correctly with abuse of LD_PRELOAD to front-end
a signal handler that catches SIGSEGV, without breaking the semantics
of legitimate signal handlers...

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  reply	other threads:[~2021-04-03 21:34 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30 17:34 John Wood
2021-03-30 18:40 ` Valdis Klētnieks
2021-04-02 12:49   ` John Wood
2021-04-03  3:50     ` Valdis Klētnieks
2021-04-03  7:02       ` John Wood
2021-04-03 21:34         ` Valdis Klētnieks [this message]
2021-04-04  9:48           ` John Wood
2021-04-04 21:10             ` Valdis Klētnieks
2021-04-05  7:31               ` John Wood
2021-04-06 23:55                 ` Valdis Klētnieks
2021-04-07 17:51                   ` John Wood
2021-04-07 20:38                     ` Valdis Klētnieks
2021-04-08  1:51                       ` Andi Kleen
2021-04-09 14:29                         ` John Wood
2021-04-09 15:06                           ` Andi Kleen
2021-04-09 16:08                             ` John Wood
2021-04-09 23:28                             ` Valdis Klētnieks
2021-04-11  8:46                               ` John Wood

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